If you have a complete tools on your workshop, there is no reason why you should not make your own aquarium, particularly if you want one of a certain size, designed for a special place. The aquariums you can buy from dealers come in a large variety of sizes and designs, certainly, but it may be that none of them will fit exactly where you want it.Say, then, that you have decided to build your own tank. The first thing you have to remember is that, the surface of watertanks is the most important things. The greater the surface of the watertanks the more oxygen is absorbed by the water and, it may seem little bit odd, fishes are just as much dependent upon oxygen as we are.Guppies for instance, need about three square inches each. Bigger fish need more space. Those of about two inches in length needing about eight square inches each, while fish running about three and half inches long need as much as twenty square inches each. There are a few exceptions to this rule. Some fishes such as Bettas, Gouramies, and Paradise Fish, take some of their oxygen directly from the air. This means that they only need half as much of the oxygen absorbing surface as the others.Do not use watertanks directly as you build or buy it. The watertanks should now be filled with water and allowed to stand for at least ten days, to test it for leaks. During this testing period we must change the water several times, as each change will help get rid of any chemicals or impurities which might poison our fishes.